Unicrimp BW and CW SWA cable glands compared side by side

🔧 Ultimate SWA Cable Glands Guide – BW vs CW, Sizes, History & Fire Safety Options

Leave a comment
Cable & Cable Accessories
Unicrimp · Wiska
Posted by: electrical4less_mirek Avatarelectrical4less_mirek

Table of contents

1. 🔍 What Are SWA Cable Glands? | SWA Cable Glands Guide

Welcome to our SWA cable glands guide — your complete reference for understanding and choosing the right armoured cable glands. Whether you’re a professional installer or a first-time buyer, this comprehensive guide to SWA armoured cable glands will help you confidently choose between BW and CW types, understand sizing, sealing, and safety standards.

2. BW vs CW – Explained in This SWA Cable Glands Guide

  • BW glands: Designed for indoor dry environments. They secure the armour but do not seal the outer sheath. Despite the name, the “W” historically stood for Brass Weather, but modern BW types are not weatherproof.¹
  • CW glands: Designed for external and wet environments. These include a compression ring and outer seal that grips the sheath, ensuring IP66 or higher protection.²

📌 Key Tip: Never use BW outdoors or try to improvise weatherproofing with sealants.

3. Gland Sizes – What Do 20S, 20, and 20L Mean?

  • 20S – For smaller cable ODs like 1.5–2.5mm²
  • 20 – Standard 2.5–4mm² cables
  • 20L – Same thread as 20 but longer length for thicker enclosures or boards³

Size always depends on your outer sheath diameter, not just the conductor size.

4. SWA Cable vs Gland Size Reference

Cable SizeApprox. ODSuggested Gland Size
1.5mm²~10mm20S
2.5mm²12–14mm20 or 20S
4mm²~14.5mm20
6mm²16–17mm20 or 25
10mm²~20mm25
16mm²~24mm25 or 32
25mm²~28mm32

👉 Always measure and cross-check with the manufacturer before installing.⁴

5. → LSF vs LSZH in SWA Cable Glands – Material Guide for Safer Installs

Most SWA glands are made from CuZn39Pb3 brass, valued for its durability, conductivity, and corrosion resistance.⁵ Reputable manufacturers offer nickel-plated options for added longevity.

Shrouds

  • PVC – Standard
  • LSF – Low Smoke & Fume
  • LSZH – Low Smoke Zero Halogen – vital in tunnels, hospitals, and railways⁶

🔥 In sensitive areas, always use LSZH to meet safety and insurance standards.

6. IP Ratings – What to Expect?

  • CW glands: IP66 or IP68 (with proper installation and sealing)⁷
  • BW glands: IP30–IP54 (not suitable for rain, condensation, or outdoors)

Correct torque is critical. Don’t over-tighten or under-seal—use a torque chart where provided.

7. 📜 History of Armoured Cable Glands | SWA Cable Glands Explained

  • 1906: First use of SWA cable in UK infrastructure⁸
  • 1919: Wiska releases first commercial brass cable glands⁹
  • 1925: Early thermoset plastic glands (e.g. Bakelite) introduced¹⁰
  • 1950s–60s: CW compression glands become industry standard¹¹

Even now, many electricians still confuse the terms “BW” and “CW”. Getting it right means better safety and full compliance.

We proudly supply:

❓ Frequently Asked Questions – SWA Cable Glands

🔍 Can I use CW glands indoors too?

Absolutely. CW glands can be used anywhere. They offer better sealing and future-proofing, especially in damp or dusty garages, basements, or outhouses.

🧯 Do LSZH and LSF matter for small installs?

They do. In areas like stairwells, schools, and enclosed lofts, low smoke and low toxicity help reduce fire-related risk. It’s a smart upgrade even for minor jobs.

📐 What happens if I use the wrong gland size?

Incorrect sizing can lead to poor earthing or failed IP protection. This could invalidate insurance or cause costly failures. Always measure your cable sheath and consult a sizing chart.

🧪 Are CW glands mandatory outdoors?

If the gland is exposed to rain, condensation, or mechanical stress, yes, CW is essential. BW should never be used outside.

📲 Follow Electrical4Less

Stay connected for deals, install demos, and trade tips:

🔗 Explore More

📚 References

  1. Doncaster Cables – BW definition
  2. CMP Products – CW sealing info
  3. Wiska UK Sizing Sheet
  4. NICEIC Installer Handbook
  5. CDA – Properties of Brass
  6. BS7671 & LSZH guidance (IET)
  7. RS Components – IP66/IP68 specs
  8. Engineering Archives UK – SWA
  9. Wiska Historical Timeline
  10. Bakelite Gland Museum Listing
  11. BS6121 adoption in mid-century specs